The pull-rods of common luggage in the market today usually have foldable structures, meaning that the pull-rods may be folded inside the luggage when not being used. The pull rod may be extended when being used. So as to make the outside of the luggage look nice, the grip of the pull-rod is usually hidden and lined up with the surface of the luggage when the pull-rod is folded inside the luggage. However, conventional luggage pull rods are not convenient because the luggage does not provide enough room for the user to grasp and pull the grip of the pull rod upward for use.
For these reasons, the industry developed a spring structure for a luggage pull-rod, as shown in FIG. 1. When the user desires to pull the grip 20 of the pull rod 10 upward, a press button 21 that is placed on the grip 20 can be pressed to make the first joint tube 11 spring upward to a predetermined distance. The internal structure, as shown in FIG. 2, includes a positioning base 110 placed at the bottom of the first joint tube 11, a spring 13 placed between the bottom of the positioning base 110, and a fixed base 120 of the second joint tube 12. The spring 13 is in a pressed state when it is pressed inside the first joint tube 11, and the positioning base 110 has a resilient jumping bean 111 that can be locked to the positioning hole 121 placed on the second joint tube 12 when protruding outward. The resilient jumping bean 111 has an oblique surface 112. When the button 21 on the grip is pressed down, a braking base 14 of the first joint tube 111 is driven downward at the same time. An oblique edge at the bottom of the braking base 14 touching the oblique surface 112 is made, and the resilient jumping bean 111 springs are driven inward. Once the resilient jumping bean 111 breaks off from the positioning hole 121, the first joint tube 11 is released, and springs up to a predetermined height, as shown in the right figure of the FIG. 2. Because of the restoring force of the spring 13, the grip 20 shown in FIG. 1 is placed in a uplifting position.
The spring structure of the luggage pull-rod is made from a two-joint structure. However, to meet the demand of a high tech user, the luggage industry has developed luggage especially for laptops. Because the height of this type of luggage is lower than regular luggage, the number of joints increases accordingly (3-5 joints). With this type of multi-joint pull-rod, the joints must interact; therefore, this structure is more complicated than the two-joint pull-rod mentioned above. The second joint tube of the multi-joint pull-rod must allow the first joint tube to slide down continually. For these reasons, its internal part cannot be placed on the fixed base mentioned above. Therefore, the spring structure of the two-joint pull-rod cannot be applied to the multi-joint pull-rod. However, there are still some issues, such as inconvenient operation when the grip mentioned above is hidden inside. Multi-joint pull-rods need further effort on the industry's part to make a break through.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement in the art to provide an improved structure that can significantly improve efficacy.
To this end, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.